/usr/share/ltsp/plugins/ltsp-build-client/common/ is in ltsp-server 5.5.1-1ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/share/ltsp/plugins/ltsp-build-client/common/000-check-paths
/usr/share/ltsp/plugins/ltsp-build-client/common/000-enable-debug
/usr/share/ltsp/plugins/ltsp-build-client/common/001-load-configuration-file
/usr/share/ltsp/plugins/ltsp-build-client/common/001-set-arch
/usr/share/ltsp/plugins/ltsp-build-client/common/001-set-exclude
/usr/share/ltsp/plugins/ltsp-build-client/common/010-etc-hosts
/usr/share/ltsp/plugins/ltsp-build-client/common/010-mount-proc
/usr/share/ltsp/plugins/ltsp-build-client/common/010-set-base
/usr/share/ltsp/plugins/ltsp-build-client/common/010-set-chroot
/usr/share/ltsp/plugins/ltsp-build-client/common/020-rootpath
/usr/share/ltsp/plugins/ltsp-build-client/common/030-update-sshkeys
/usr/share/ltsp/plugins/ltsp-build-client/common/035-update-kernels
/usr/share/ltsp/plugins/ltsp-build-client/common/091-unmount-dirs